Align the top of the largeIcon with the top of the expander when expanded.

This looks a tad better, and adds some slight motion when expanding which was desired by the motion team.
We're still investigating moving this down below the expander.

Bug: 181048615
Test: expand/collapse a notification with an icon
Change-Id: Ic47b41e7295a490820eafa1a3faa592861d3bc30